FileAssociationHelper.cs

using System;
using Microsoft.Win32;

namespace LinView
{
    /// <summary>
    /// 负责系统级文件关联的读写（需要管理员权限）。
    /// </summary>
    public static class FileAssociationHelper
    {
        /// <summary>把某个扩展名关联到本程序。</summary>
        public static void Associate(string ext)
        {
            string exePath = System.Windows.Forms.Application.ExecutablePath;

            // 1. 注册 ProgID
            using (var progId = Registry.ClassesRoot.CreateSubKey(AppConstants.ProgId))
            {
                progId.SetValue("", AppConstants.ProgIdDescription);
                using var icon = progId.CreateSubKey("DefaultIcon");
                icon.SetValue("", $"\"{exePath}\",0");
                using var cmd = progId.CreateSubKey(@"shell\open\command");
                cmd.SetValue("", $"\"{exePath}\" \"%1\"");
            }

            // 2. 把扩展名默认指向 ProgID
            using (var extKey = Registry.ClassesRoot.CreateSubKey(ext))
            {
                extKey.SetValue("", AppConstants.ProgId);
            }

            // 3. 同时写入 OpenWithProgids，保证"打开方式"列表里也有
            using (var openWith = Registry.ClassesRoot.CreateSubKey($@"{ext}\OpenWithProgids"))
            {
                openWith.SetValue(AppConstants.ProgId, Array.Empty<byte>(), RegistryValueKind.None);
            }
        }

        /// <summary>取消某个扩展名与本程序的关联。</summary>
        public static void Unassociate(string ext)
        {
            using (var extKey = Registry.ClassesRoot.OpenSubKey(ext, writable: true))
            {
                if (extKey?.GetValue("") as string == AppConstants.ProgId)
                    extKey.DeleteValue("", throwOnMissingValue: false);
            }

            using (var openWith = Registry.ClassesRoot.OpenSubKey($@"{ext}\OpenWithProgids", writable: true))
            {
                openWith?.DeleteValue(AppConstants.ProgId, throwOnMissingValue: false);
            }
        }
    }
}